This interesting historical sidenote comes via Shorpy. This is inventor Charles Francis Jenkins, who later became an early pioneer of television and founder of SMPTE, the Society of Motion Picture and Television Engineers, who, though they may not be a household name, created color bars for calibrating screen color that everyone will recognize. He’s demonstrating a 1925 prototype of motion picture broadcasting that creates moving pictures when hooked up to the radio, which he first described it in 1913, but didn’t build and demonstrate till the early 1920s.
From the description, I believe that the box on the right is projecting onto the white space inside the frame on the wall, with a reflector in the raised portion of the box redirecting light from a bulb beneath it. There’s most likely a spinning disk in the semi-circle, driven by a motor that takes up the rest of the box. My initial thought was that the disk contained the frames of the animation of the girl, but after reading more, I don’t believe that’s the case – the image is actually being transmitted and created on the fly. This is mechanical television, which is a different beast from the television technology that soon dominated, Farnsworth’s electronic television, and I’m not certain how the images are being created from the transmitted signal.
Jenkins’ history with motion pictures stretches back to 1894, when he started work on a project that would later be acquired by Edison, and hundreds of patents later, turned towards military and commercial modifications for aircraft and ships. But he’s also responsible for that spiral-formed cardboard box your Quaker Oats come in.